Invention Grant
- Patent Title: Dual check valve
- Patent Title (中): 双止回阀
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Application No.: US12615068Application Date: 2009-11-09
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Publication No.: US08668015B2Publication Date: 2014-03-11
- Inventor: Gerald Leeb
- Applicant: Gerald Leeb
- Agency: Pedersen and Company, PLLC
- Agent Ken J. Pedersen; Barbara S. Pedersen
- Priority: CA2540499 20060317
- Main IPC: E21B34/08
- IPC: E21B34/08

Abstract:
A check valve comprising a section of a drill string, a flapper valve positioned within and concentric to the section of the drill string, and a piston valve positioned within and concentric to the section of the drill string. The flapper valve allows fluid flow in a first direction through an inner portion of a cross-section of the section of the drill string and not allowing fluid flow in a second direction, and the piston check valve allowing fluid flow in the first direction through an outer portion of the cross-section of the section of the drill string and not allowing fluid flow in the second direction, where the first portion and the second portion of the cross-section of the section of the drill string are mutually exclusive.
Public/Granted literature
- US20100116503A1 DUAL CHECK VALVE Public/Granted day:2010-05-13
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